The present invention relates to a damper for a bicycle and in particular to a pull shock damper for a bicycle which is employed in particular for damping shocks at the rear wheel of a bicycle. A pull shock damper is a damper where the piston rod is pulled out of the damper housing as the wheel deflects. In conventional dampers, however, the piston rod enters the damper housing as the wheel deflects. Although the invention will be described below substantially with reference to pull shock dampers, the invention may, however, likewise be employed for conventional dampers.
In the prior art for example U.S. Pat. No. 7,219,881 B2 disclosed a pull shock damper described therein with reference to FIG. 31. The known damper comprises one gas-filled negative spring and two oil- and gas-filled positive springs. The negative spring serves to linearize the load-deflection curves of the damper. On the whole the known damper is provided with three air chambers the filling pressures of which can be separately adjusted via separate valves. Due to the required damping characteristics a suitable filling pressure for operation is approximately 30% lower in the negative chamber than in the positive chamber.
It has been found that due to the manifold setting options even some experienced users may set inappropriate pressure relations in these dampers which will impair the riding properties and lead to undesirable spring and damping results since the force of the negative spring tends to be too high or too low.